The present invention relates to fibrous products for use in the polishing or other treatment of surfaces with abrasives, chemicals, and the like and to processes for producing same.
Industry has for many years utilized techniques for cutting and polishing glass, metals, stones, crystals and the like in which a pad, substrate or the like is applied against a surface to be treated and with an abrasive material such as cerium oxide, aluminum oxide and the like located therebetween, normally in a slurry form. Pressure applied by the polishing pad or other substrate against the abrasive matrials carried by the slurry imparts a cutting affect on the surface, and depending upon the parameters of the process, a surface being treated may be cut, ground, and/or polished. In similar fashion certain polishing operations have been conducted with chemical formulations only.
Materials to be cut, ground or polished are virtually limitless and include metals, glasses, polymeric compositions, stones, ceramics, crystals and the like. The degree of cutting, grinding and/or polishing is determined by the particular abrasives being used, the particular pads or substrates employed and the particular pressures involved to achieve the desired result.
Certain techniques are designed solely to present a product having a pleasing, aesthetic surface. In many other cases, however, significant criticality is attached to the ultimate finished surface to enable the article or product to function as intended, such as for example, picture tubes for television sets or other video equipment, optical lenses, gem stones, electronic components, and the like, including initial preparation as well as removal of defects therefrom.
The polishing pads are substrates used in the manner aforesaid, and have taken various and sundry forms from a flat planar surface having a predetermined shape to endless bands and/or discrete particles secured to a rotary support member. Likewise, when the particular product or article to be ground and/or polished has a particular three-dimensional shape as opposed to a planar surface, such often dictates the particular size, shape, and/or configuration of the polishing pad that is to be employed.
Many attempts have heretofore been made to fabricate polishing pads of various and sundry shapes and materials to accommodate for the wide variety of uses noted above, and in general, have succeeded in affording some economic and/or technical improvement in the then state of the art processes. Though such improvements have heretofore been made, problems continue to exist for various and sundry reasons. Notably, needled natural and synthetic fibrous felts have been produced and utilized as polishing pads though historically such products have been lacking in uniformity of density, porosity, and the like. Furthermore, historically there have been limits to the thickness of such needled fibrous products though attempts have been made to tack plural layers together to build up a thicker composite polishing pad. Under such tacking conditions needling into adjacent fibrous layers is limited, however, and discrete layers remain with a lack of total cohesiveness therebetween leading to possible delamination of the polishing pad which, of course, would require discarding of same, and may destroy the product or products being treated.
Other attempts have been made to produce composite pads in which discrete fibrous layers have been adhesively secured together. Again, the adhesive interfacial layers present a different effect in the working of abrasives or the like across a work surface than the fibrous pad, leading to possible changes in surface characteristics. Likewise, adhesive bonds are subject fo fail, leading to delamination with same attendant results as noted above.
Other techniques utilized in producing fibrous polishing pads include the carding or other aligning of batts of fibers followed by needling of the batt. Certain of the batts have been built up by the cross-lapping of fibrous webs, followed by needling once the webs of desired thickness weight or the like was obtained. These types of technique are limited to very thin products due to initial fiber bulk.
In still other operations, attempts have been made to orient the fibers in a polishing pad to enhance the effective use of same.
All in all, therefore, considerable effort has been expended in attempting to improve the art of fibrous pads or structures for use in cutting, grinding or polishing of various surfaces.
In recent years, following at least the advent of the poromeric synthetic leather materials the fibrous pads or substrates have been impregnated with porous elastomeric materials. The elastomeric materials employed have often been urethane based and have been variously applied to the fibrous materials from both solvent and aqueous systems. Key to application of the elastomeric materials has been placement of the cured elastomer throughout the fibrous base with a proper field of pores, normally microscopic in size to achieve a uniformly impregnated structure with uniform porosity.
Porosity becomes important in actual use of the finished product in the mechanism of working of the abrasives across the work surface. Notably, as the pad is moved under pressure across the work surface, porosities of the pad continually pick up and expel abrasive slurry in a "pumping action" which adds to uniformity of the action.
Other known-prior art includes U.S. Pat. Nos. 3,000,757; 3,067,483;, 3,100,721; 3,180,853; 3,208,875; 3,284,275; 3,536,553; 3,499,250; 3,504,457; 3,581,439; and 4,728,552, all of which relate to fibrous substrates impregnated with elastomeric materials for polishing operations and the like.
The fibrous structure of the present invention, represents improvement over all of the above prior art and is neither taught nor suggested thereby.